Studies in histocompatibility

Mechanisms of allorecognition and xenorecognition in transplantation

Foreign antigen recognition is the ability of immune cells to distinguish self from nonself, which is crucial for immune responses in both invertebrates and vertebrates. In vertebrates, T cells play a pivotal role in graft rejection by recognizing alloantigens presented by antigen-presenting cells through direct, indirect, or semidirect pathways. B cells also significantly contribute to the indirect presentation of antigens to T cells. Innate immune cells, such as dendritic cells, identify pathogen- or danger-associated molecular patterns through pattern recognition receptors, thereby facilitating effective antigen presentation to T cells. Recent studies have shown that innate immune cells, including macrophages and NK cells, can recognize allogeneic or xenogeneic antigens using immune receptors like CD47 or activating NK receptors, instead of pattern recognition receptors. Additionally, macrophages and NK cells are capable of exhibiting memory responses to alloantigens, although these responses are shorter than those of adaptive memory. T cells also recognize xenoantigens through either direct or indirect presentation. Notably, macrophages and NK cells can directly recognize xenoantigens via surface immune receptors in an antibody-independent manner, or they can be activated in an antibody-dependent manner. Advances in our understanding of the recognition mechanisms of adaptive and innate immunity against allogeneic and xenogeneic antigens may improve our understanding of graft rejection.

Genetic and functional diversity of allorecognition receptors in the urochordate, Botryllus schlosseri

Allorecognition in Botryllus schlosseri is controlled by a highly polymorphic locus (the fuhc), and functionally similar to missing-self recognition utilized by Natural Killer cells-compatibility is determined by sharing a self-allele, and integration of activating and inhibitory signals determines outcome. We had found these signals were generated by two fuhc-encoded receptors, called fester and uncle fester. Here we show that fester genes are members of an extended family consisting of >37 loci, and co-expressed with an even more diverse gene family-the fester co-receptors (FcoR). The FcoRs are membrane proteins related to fester, but include conserved tyrosine motifs, including ITIMs and hemITAMs. Both genes are encoded in highly polymorphic haplotypes on multiple chromosomes, revealing an unparalleled level of diversity of innate receptors. Our results also suggest that ITAM/ITIM signal integration is a deeply conserved mechanism that has allowed convergent evolution of innate and adaptive cell-based recognition systems.

The pharmacogenomics of carbamazepine-induced cutaneous adverse drug reaction in the South of Vietnam

Background: The relationship between HLA-B*15:02 and Severe Cutaneous Adverse Reactions was rigorously examined in Japanese, Han Chinese, Thais, and Caucasians. However, the number of studies about this topic in Vietnamese population is still limited and mostly focuses on the North of Vietnam. Objective: This study aims to clarify the genetic culprit of SCARs in Vietnamese population, particularly in the South of Vietnam, and to validate our result by a meta-analysis about this topic in Vietnamese. Method: A retrospective case-control study with 37 patients treated with carbamazepine monotherapy. Statistical calculation and meta-analysis were performed by R software. Result: HLA-B*15:02 increases the risk of SJS 12.5 times higher in CBZ-treated patients (p-value = 0.017). However, this allele has no impact on MCARs (Mild Cutaneous Adverse Reactions) of CBZ. The number needed to test and the number needed to genotype is two and nine patients respectively. Conclusion: This study recommends more investigations about the cost-effectiveness of this test to accelerate the protection of Southern Vietnamese from SCARs.

Pathways of Antigen Recognition by T Cells in Allograft Rejection

The adaptive immune response leading to the rejection of allogeneic transplants is initiated and orchestrated by recipient T cells recognizing donor antigens. T-cell allorecognition is mediated via 3 distinct mechanisms: the direct pathway in which T cells recognize allogeneic major histocompatibility complex (MHC) molecules on donor cells, the indirect pathway through which T cells interact with donor peptides bound with self-MHC molecules on recipient antigen-presenting cells, and the recently described semidirect pathway whereby T cells recognize donor MHC proteins on recipient antigen-presenting cells. In this article, we present a description of each of these allorecognition pathways and discuss their role in acute and chronic rejection of allogeneic transplants.

Cancer Immunology and Immunotherapy: From Defining Basic Immunology to Leading the Fight Against Cancer

The past decade has seen the advent and widespread use of several immunotherapeutic modalities that have markedly improved treatment outcomes for patients with various cancers. Nevertheless, the study of cancer immunology traces its roots back to the inception of modern immunology, and played a critical role in the of discovery of central immunological concepts and development of key technologies and methodologies and that have propelled advances in all areas of immunology.

Comparative assessment of immunological tolerance in fish with natural immunodeficiency

Natural occurrences of immunodeficiency by definition should lead to compromised immune function. The major histocompatibility complexes (MHC) are key components of the vertebrate adaptive immune system, charged with mediating allorecognition and antigen presentation functions. To this end, the genomic loss of the MHC II pathway in Syngnathus pipefishes raises questions regarding their immunological vigilance and allorecognition capabilities. Utilising allograft and autograft fin-transplants, we compared the allorecognition immune responses of two pipefish species, with (Nerophis ophidion) and without (Syngnathus typhle) a functional MHC II. Transcriptome-wide assessments explored the immunological tolerance and potential compensatory measures occupying the role of the absent MHC II. Visual observations suggested a more acute rejection response in N. ophidion allografts compared with S. typhle allografts. Differentially expressed genes involved in innate immunity, angiogenesis and tissue recovery were identified among transplantees. The intriguing upregulation of the cytotoxic T-cell implicated gzma in S. typhle allografts, suggests a prominent MHC I related response, which may compensate for the MHC II and CD4 loss. MHC I related downregulation in N. ophidion autografts hints at an immunological tolerance related reaction. These findings may indicate alternative measures evolved to cope with the MHC II genomic loss enabling the maintenance of appropriate tolerance levels. This study provides intriguing insights into the immune and tissue recovery mechanisms associated with syngnathid transplantation, and can be a useful reference for future studies focusing on transplantation transcriptomics in non-model systems.

The MHC class I MICA gene is a histocompatibility antigen in kidney transplantation

The identity of histocompatibility loci, besides human leukocyte antigen (HLA), remains elusive. The major histocompatibility complex (MHC) class I MICA gene is a candidate histocompatibility locus. Here, we investigate its role in a French multicenter cohort of 1,356 kidney transplants. MICA mismatches were associated with decreased graft survival (hazard ratio (HR), 2.12; 95% confidence interval (CI): 1.45–3.11; P < 0.001). Both before and after transplantation anti-MICA donor-specific antibodies (DSA) were strongly associated with increased antibody-mediated rejection (ABMR) (HR, 3.79; 95% CI: 1.94–7.39; P < 0.001; HR, 9.92; 95% CI: 7.43–13.20; P < 0.001, respectively). This effect was synergetic with that of anti-HLA DSA before and after transplantation (HR, 25.68; 95% CI: 3.31–199.41; P = 0.002; HR, 82.67; 95% CI: 33.67–202.97; P < 0.001, respectively). De novo-developed anti-MICA DSA were the most harmful because they were also associated with reduced graft survival (HR, 1.29; 95% CI: 1.05–1.58; P = 0.014). Finally, the damaging effect of anti-MICA DSA on graft survival was confirmed in an independent cohort of 168 patients with ABMR (HR, 1.71; 95% CI: 1.02–2.86; P = 0.041). In conclusion, assessment of MICA matching and immunization for the identification of patients at high risk for transplant rejection and loss is warranted.

Analysis of a multicenter cohort of kidney transplants shows that mismatches in the MICA locus and the presence of anti-MICA donor-specific antibodies are associated with reduced graft survival and increased rejection.

HLA-G and single nucleotide polymorphism (SNP) associations with cancer in African populations: Implications in personal medicine

The immune system plays an important role in protecting the body against malignancy. During cancer immunoediting, the immune system can recognize and keep checking the tumor cells by down-expression of some self-molecules or by increasing expression of some novel molecules. However, the microenvironment created in the course of cancer development hampers the immune ability to recognize and destroy the transforming cells. Human Leukocyte Antigen G (HLA-G) is emerging as immune checkpoint molecule produced more by cancer cells to weaken the immune response against them. HLA-G is a non-classical HLA class I molecule which is normally expressed in immune privileged tissues as a soluble or membrane-bound protein. HLA-G locus is highly polymorphic in the non-coding 3′ untranslated region (UTR) and in the 5′ upstream regulatory region (5′ URR). HLA-G expression is controlled by polymorphisms located in these regions, and several association studies between these polymorphic sites and disease predisposition, response to therapy, and/or HLA-G protein expression have been reported. Various polymorphisms are demonstrated to modulate its expression and this is increasingly finding more significance in cancer biology. This review focuses on the relevance of the HLA-G gene and its polymorphisms in cancer development. We highlight population genetics of HLA-G as evidence to espouse the need and importance of exploring potential utility of HLA-G in cancer diagnosis, prognosis and immunotherapy in the currently understudied African population.

Mouse Watch: A Cautionary Tale

In this issue of Immunity, Chisolm et al. (2019) issue a "three-alarm fire" warning to the immunology research community of unexpectedly widespread genetic variation in widely used congenic mouse strains and provide a simple method to identify such a variation through a re-analysis of existing RNA-seq and ChIP-seq datasets.

The role of MHC genes in contagious cancer: the story of Tasmanian devils

The Tasmanian devil, a marsupial species endemic to the island of Tasmania, harbours two contagious cancers, Devil Facial Tumour 1 (DFT1) and Devil Facial Tumour 2 (DFT2). These cancers pass between individuals in the population via the direct transfer of tumour cells, resulting in the growth of large tumours around the face and neck of affected animals. While these cancers are rare, a contagious cancer also exists in dogs and five contagious cancers circulate in bivalves. The ability of tumour cells to emerge and transmit in mammals is surprising as these cells are an allograft and should be rejected due to incompatibility between Major Histocompatibility Complex (MHC) genes. As such, considerable research has focused on understanding how DFT1 cells evade the host immune system with particular reference to MHC molecules. This review evaluates the role that MHC class I expression and genotype plays in allowing DFT1 to circumvent histocompatibility barriers in Tasmanian devils. We also examine recent research that suggests that Tasmanian devils can mount an immune response to DFT1 and may form the basis of a protective vaccine against the tumour.

Controlling complexity: the clinical relevance of mouse complex genetics

Experimental animal models are essential to obtain basic knowledge of the underlying biological mechanisms in human diseases. Here, we review major contributions to biomedical research and discoveries that were obtained in the mouse model by using forward genetics approaches and that provided key insights into the biology of human diseases and paved the way for the development of novel therapeutic approaches.

Haplessly hoping: macaque major histocompatibility complex made easy

Major histocompatibility complex (MHC) gene products control the repertoire of T cell responses that an individual may create against pathogens and foreign tissues. This text will review the current understanding of MHC genetics in nonhuman primates, with a focus on Mauritian-origin cynomolgus macaques (Macaca fascicularis) and Indian-origin rhesus macaques (Macaca mulatta). These closely related macaque species provide important experimental models for studies of infectious disease pathogenesis, vaccine development, and transplantation research. Recent advances resulting from the application of several cost effective, high-throughput approaches, with deep sequencing technologies have revolutionized our ability to perform MHC genotyping of large macaque cohorts. Pyrosequencing of cDNA amplicons with a Roche/454 GS Junior instrument, provides excellent resolution of MHC class I allelic variants with semi-quantitative estimates of relative levels of transcript abundance. Introduction of the Illumina MiSeq platform significantly increased the sample throughput, since the sample loading workflow is considerably less labor intensive, and each instrument run yields approximately 100-fold more sequence data. Extension of these sequencing methods from cDNA to genomic DNA amplicons further streamlines the experimental workflow and opened opportunities for retrospective MHC genotyping of banked DNA samples. To facilitate the reporting of MHC genotypes, and comparisons between groups of macaques, this text also introduces an intuitive series of abbreviated rhesus MHC haplotype designations based on a major Mamu-A or Mamu-B transcript characteristic for ancestral allele combinations. The authors believe that the use of MHC-defined macaques promises to improve the reproducibility, and predictability of results from pre-clinical studies for translation to humans.

Major Histocompatibility Complex (MHC) markers in conservation biology

Human impacts through habitat destruction, introduction of invasive species and climate change are increasing the number of species threatened with extinction. Decreases in population size simultaneously lead to reductions in genetic diversity, ultimately reducing the ability of populations to adapt to a changing environment. In this way, loss of genetic polymorphism is linked with extinction risk. Recent advances in sequencing technologies mean that obtaining measures of genetic diversity at functionally important genes is within reach for conservation programs. A key region of the genome that should be targeted for population genetic studies is the Major Histocompatibility Complex (MHC). MHC genes, found in all jawed vertebrates, are the most polymorphic genes in vertebrate genomes. They play key roles in immune function via immune-recognition and -surveillance and host-parasite interaction. Therefore, measuring levels of polymorphism at these genes can provide indirect measures of the immunological fitness of populations. The MHC has also been linked with mate-choice and pregnancy outcomes and has application for improving mating success in captive breeding programs. The recent discovery that genetic diversity at MHC genes may protect against the spread of contagious cancers provides an added impetus for managing and protecting MHC diversity in wild populations. Here we review the field and focus on the successful applications of MHC-typing for conservation management. We emphasize the importance of using MHC markers when planning and executing wildlife rescue and conservation programs but stress that this should not be done to the detriment of genome-wide diversity.

A compendium of the mouse mammary tumor biologist: from the initial observations in the house mouse to the development of genetically engineered mice

For over a century, mouse mammary tumor biology and the associated mouse mammary tumor virus (MMTV) have served as the foundation for experimental cancer research, in general, and, in particular, experimental breast cancer research. Spontaneous mouse mammary tumors were the basis for studies of the natural history of neoplasia, oncogenic viruses, host responses, endocrinology and neoplastic progression. However, lacking formal proof of a human mammary tumor virus, the preeminence of the mouse model faded in the 1980s. Since the late 1980s, genetically engineered mice (GEM) have proven extremely useful for studying breast cancer and have become the animal model for human breast cancer. Hundreds of mouse models of human breast cancer have been developed since the first demonstration in 1984. The GEM have attracted a new generation of molecular and cellular biologists eager to apply their skill sets to these surrogates of the human disease. Newcomers often enter the field without an appreciation of the origins of mouse mammary tumor biology and the basis for many of the prevailing concepts. Our purpose in writing this compendium is to extend an "olive branch" while simultaneously deepen the knowledge of the novice mouse mammary tumor biologist as they journey into a field rich in pathology and genetics spanning several centuries.

Pregnancy immunogenetics: NK cell education in the womb?

During embryo implantation and initiation of pregnancy, uterine NK (uNK) cells engage invasive fetal trophoblasts to remodel vessels that conduct blood to the placenta. This partnership, involving uNK cell receptors that recognize HLA-C ligands on trophoblasts, varies the course of human pregnancy because the genes for both receptors and ligands are extraordinarily diverse. Several pregnancy disorders are attributed to insufficient trophoblast invasion and the limitation it imposes on human reproduction. Previously, a particular combination of fetal HLA-C and maternal inhibitory uNK cell receptor was associated with predisposition for preeclampsia. In this issue of the JCI, Hiby and colleagues extend this correlation to recurrent miscarriage and fetal growth restriction, revealing the common mechanism underlying these common pregnancy syndromes. Equally important, they show that mothers with an activating receptor of similar specificity to the inhibitory receptor are less likely to suffer disordered pregnancy.

Immunological tolerance and tumor rejection in embryo-aggregated chimeric mice - lessons for tumor immunity

Background

Rejection of transplanted tumors by the immune system is a rare event in syngeneic hosts, and is considered to be dependent on the local interaction of defensive immune reactions and tumor tolerance mechanisms. Here, we have enlisted the aid of a unique set of embryo-aggregated lineage chimeric mice derived from C57/BL6 and FVB donors to study the interplay between local and systemic tumor immunity and tolerance in rejection of mouse B16 melanoma cells, syngeneic to the C57/BL6 donor strain.

Methods

Two variants of embryo-aggregated chimeric mice with either variable or no contribution of C57-derived cells to their skin were generated by the fusion of different ratios of morula stage blastomers. Chimeric mice were analyzed for s.c. growth of B16 tumors in comparison to their respective donor strains as well as normal F1 hybrids, and the relative frequencies of cellular components of the immune system by FACS analysis of peripheral blood or lymph node cells.

Results

B16 tumors grew significantly faster in mice with full chimerism in their skin as compared to syngeneic C57 or semi-syngeneic C57 × FVB F1 hosts. In contrast, s.c. tumor growth was either absent or significantly reduced in chimeric mice lacking C57-derived cells in their skin, but tolerant to C57 tissue in other organs. Comparison of the relative frequencies of various immune cells in the periphery via FACS-analysis did not reveal any significant differences between the two types of chimeric mice with respect to their donor strains.

Conclusion

Our data suggest a complex interplay between mechanisms of local peripheral tolerance and innate antitumor mechanisms possibly involving NK cell allorecognition as a basis for the differential growth or rejection of B16 tumors in these unique chimeric mice, which we suggest to constitute a valuable new model system for the study of immune-mediated tumor rejection.

Fine mapping of a major locus on chromosome 10 for exploratory and fear-like behavior in mice

Advanced intercross lines (AIL) and interval-specific congenic strains (ISCS) were used to fine map previously coarsely defined quantitative trait loci (QTL) on Chromosomes 1, 10, and 19, influencing behaviors in the open Field (OF) and light-dark (LD) paradigms in mice. F12(A x B) AIL mice (N = 1130) were phenotyped, genotyped, and mapped. The ISCS were studied only in the telomeric Chromosome 10 region of interest, containing the exploratory and excitability QTL1 (Exq1). The Chromosome 10 Exq1 and Chromosome 19 Exq4 loci mapped robustly in the AIL. The most significant QTL findings (2.0 LOD score intervals; peak; LOD score) came from the TD15 and LD transitions traits, yielding estimated intervals of 2.2 cM for Exq1 (71.3-73.5 cM; peak 72.3 cM; LOD 11.9) and 9.0 cM for Exq4 (29.0-38.2 cM; peak 34 cM; LOD 4.2). The replicated QTLs on Chromosome 1 failed to map in this AIL population. The ISCS data confirmed Exq1 loci in general. However, the ISCS data were complex and less definitive for localizing the Exq1 loci. These exploratory and fear-like behaviors result from inheriting "many small things," namely, QTL explaining 2%-7% of the phenotypic variance. These results highlight the challenges of positionally cloning loci of small effect for complex traits. In particular, fine-mapping success may depend on the genetic architecture underlying complex traits.

Comparative genomics of major histocompatibility complexes

The major histocompatibility complex (MHC) is a gene dense region found in all jawed vertebrates examined to date. The MHC contains a high percentage of immune genes, in particular genes involved in antigen presentation, which are generally highly polymorphic. The region plays an important role in disease resistance. The clustering of MHC genes could be advantageous for co-evolution or regulation, and its study in many species is desirable. Even though some linkage of MHC genes is apparent in all gnathostomes, the genomic organization can differ greatly by species, suggesting rapid evolution of MHC genes after divergence from a common ancestor. Previous reviews of comparative MHC organization have been written when relatively fragmentary sequence and mapping data were available on many species. This review compares maps of MHC gene orders in commonly studied species, where extensive sequencing has been performed.

The effects of chemotherapeutics on cellular metabolism and consequent immune recognition

Awidely held view is that oncolytic agents induce death of tumor cells directly. In this report we review and discuss the apoptosis-inducing effects of chemotherapeutics, the effects of chemotherapeutics on metabolic function, and the consequent effects of metabolic function on immune recognition. Finally, we propose that effective chemotherapeutic and/or apoptosis-inducing agents, at concentrations that can be achieved physiologically, do not kill tumor cells directly. Rather, we suggest that effective oncolytic agents sensitize immunologically altered tumor cells to immune recognition and immune-directed cell death.

An interval tightly linked to but distinct from the H2 complex controls both overt diabetes (Idd16) and chronic experimental autoimmune thyroiditis (Ceat1) in nonobese diabetic mice

The major histocompatibility complex (MHC) has long been associated with predisposition to several autoimmune diseases, including type 1 diabetes and autoimmune thyroiditis. In type 1 diabetes, a primary role has been assigned to class II genes, both in humans and in the nonobese diabetic (NOD) mouse model. However, an involvement of other tightly linked genes is strongly suspected. Here, through two independent sets of experiments, we provide solid evidence for the existence of at least one such gene. First, using a new recombinant congenic NOD strain, R114, we definitively individualized the Idd16 locus from the MHC in a 6-cM interval proximal to H2-K. It affords almost complete protection against diabetes and is associated with delayed insulitis. Second, by genome scan, we mapped non-H2 genes associated with the highly penetrant form of chronic experimental autoimmune thyroiditis (EAT) that is elicited in NOD and NOD.H2(k) mice by immunization with thyroglobulin. We identified one major dominant locus, Ceat1, on chromosome 17, overlapping with Idd16. Most importantly, R114 recombinant congenic mice challenged with thyroglobulin did not develop chronic EAT. This new major region defined by both Idd16 and Ceat1 might thus concur to the unique strength of the MHC in autoimmune susceptibility of NOD mice.

Specific HR-associated recognition of secreted proteins from Cladosporium fulvum occurs in both host and non-host plants

The resistance of tomato (Lycopersicon esculentum) to the pathogenic fungus Cladosporium fulvum complies with the gene-for-gene concept. Host resistance is based on specific recognition of extracellular fungal proteins, resulting in a hypersensitive response (HR). Five proteins secreted by C. fulvum were purified and the encoding cDNA clone was obtained from two novel ones among them. Various tomato breeding lines and accessions of Lycopersicon pimpinellifolium were tested for their recognitional specificity by injection of the purified proteins or potato virus X-based expression of the cDNA. We found that HR-associated recognition of one or more of these proteins, in addition to recognition of the race-specific elicitors AVR4 and AVR9 of C. fulvum, occurs among Lycopersicon species. Studies on the inheritance of this recognition confirmed that single dominant genes are involved. Furthermore, one of the extracellular proteins of C. fulvum is specifically recognized by Nicotiana paniculata, which is not a host for C. fulvum. These results indicate that plants have a highly effective surveillance system for the presence of 'foreign' proteins, which, together with the high mutation rate of pathogens, can explain the complex gene-for-gene relationships frequently observed in pathosystems.

Molecular and immunological approaches to mammalian fertilization

By means of hybridoma technology, we obtained six hydriboma cell lines producing monoclonal antibody (mAb) to porcine zona pellucid (ZP), two of which recognizes the steric structure of common antigens between porcine ZP and humans. Furthermore, we have analyzed all or partial structures of N- and O-linked sugar chains of ZP glycprotein from porcine or murine oocytes. Then, we have clarified that beta-galactose and Le(X) residues on ZP played the binding roles to sperm cells in porcine and murine fertilization. We have also succeeded Sp38 cDNA cloning from cDNA library of porcine testis. We found that Sp38 protein bind to porcine ZP2 and expressed in murine and human sperm cells. Corresponding to the presence of major histocompatibility complex (MHC) class II on murine sperm, CD4 on the murine egg plasma membrane was clearly shown by indirect IIF and immunoprecipitation test. Furthermore, the transcriptional expression of CD4/p56(lck) in eggs was confirmed by RT-PCR method. In addition, the p56(lck) associated with CD4 underneath the plasma membrane of eggs was autophosphorylated after cross-linking of CD4 with anti CD4 mAb. The binding between eggs or Sf9-CD4 cells labeled with anti-CD4 mAb and sperm cells labeled with anti-monomorphic region of class II mAb was completely blocked. Considering these findings together with the fact that an interspecies' heterogeneity is present in CD4 amino acid sequence at the interactive site with class II, we elucidated that one of species' specific intercellular adhesions between two gametes at the fusion step in fertilization is definitely mediated by class II located on the posterior region of sperm head and CD4/p56(lck) complex on the plasma membrane of egg.

Does the oxidative/glycolytic ratio determine proliferation or death in immune recognition?

Here we discuss the possibility that the way cells utilize fuel(s) for energy confers the properties that can be recognized by the immune system and, reciprocally, that recognition by the immune system can alter the balance of the cell's energy metabolism. We propose that immune recognition, of somatic cells via MHC can alter the their energy metabolism and induce a metabolic shift. We demonstrate the reciprocal relationship that inducing a shift in metabolism toward glycolysis by supplying glucose and insulin results in the upregulation of immunologically recognizable molecules such as cell surface Fas. Thus, immune recognition can induce metabolic deviation. Metabolic deviation can result in altered immune recognition and ultimately in cell proliferation, cell differentiation, or cell death.

gamma delta+ T cells regulate major histocompatibility complex class II(IA and IE)-dependent susceptibility to coxsackievirus B3-induced autoimmune myocarditis

Coxsackievirus B3 (CVB3) infection induces myocardial inflammation and myocyte necrosis in some, but not all, strains of mice. C57BL/6 mice, which inherently lack major histocompatibility complex (MHC) class II IE antigen, develop minimal cardiac lesions despite high levels of virus in the heart. The present experiments evaluate the relative roles of class II IA and IE expression on myocarditis susceptibility in four transgenic C57BL/6 mouse strains differing in MHC class II antigen expression. Animals lacking MHC class II IE antigen (C57BL/6 [IA+ IE-] and ABo [IA- IE-]) developed minimal cardiac lesions subsequent to infection despite high concentrations of virus in the heart. In contrast, strains expressing IE (ABo Ealpha [IA- IE+] and Bl.Tg.Ealpha [IA+ IE+]) had substantial cardiac injury. Myocarditis susceptibility correlated to a Th1 (gamma interferon-positive) cell response in the spleen, while disease resistance correlated to a preferential Th2 (interleukin-4-positive) phenotype. Vgamma/Vdelta analysis indicates that distinct subpopulations of gamma delta+ T cells are activated after CVB3 infection of C57BL/6 and Bl.Tg.Ealpha mice. Depletion of gamma delta+ T cells abrogated myocarditis susceptibility in IE+ animals and resulted in a Th1-->Th2 phenotype shift. These studies indicate that the MHC class II antigen haplotype controls myocarditis susceptibility, that this control is most likely mediated through the type of gamma delta T cells activated during CVB3 infection, and finally that different subpopulations of gamma delta+ T cells may either promote or inhibit Th1 cell responses.

Drug resistance results in alterations in expression of immune recognition molecules and failure to express Fas (CD95)

It is demonstrated that methotrexate/cisplatin-sensitive L1210 cells express low levels of major histocompatibility complex (MHC) class II relative to the high levels expressed on methotrexate (MTX)/cisplatin-resistant L1210/DDP cells. L1210 cells express cell-surface Fas, while the L1210/DDP cells express no cell-surface Fas. Expression of costimulatory molecules B7-1/B7-2 and Fas is increased on L1210 cells, but not L1210/DDP, in the presence of methotrexate or trimetrexate (TMTX). Therefore, a component of the mechanism of action of some anti-cancer agents may be to facilitate immune recognition and T cell-directed, Fas-induced cell death. Loss of cell-surface Fas expression and failure of Fas (CD95)-dependent apoptotic death has been observed when cells develop drug resistance. The defect in apoptosis can be overcome by anti-cancer agents or experimental manipulation that induce Fas expression on the drug-resistant cells.

Failure to reject an allografted tumor after elimination of macrophages in mice

After an i.p. transplantation of an allogeneic tumor (Meth A) to C57BL/6 mice, a macrophage (M phi)-rich, non-T, non-NK cell population is induced as the major infiltrate and cytotoxic cells. We here evaluated the role of the M phi s in the rejection of allografted Meth A cells and characterized the M phi s in comparison with other well-known M phi s. At all time intervals after transplantation, the highest cytotoxic activities against Meth A tumor were obtained with the M phi-rich population. In addition, the lymphocyte-rich population had a significant but low cytotoxic activity, whereas two other population types, granulocytes and large granular cells, were inactive. When the M phi-rich or the T cell-depleted M phi-rich population was i.p. transplanted simultaneously with Meth A cells into untreated C57BL/6 mice, the tumor cells were rejected without growth. After specific elimination of M phi s by in vivo application of dichloromethylene diphosphonate-containing liposomes, the cytotoxic activity against Meth A cells was hardly induced at the transplantation site of Meth A cells and the allografted Meth A tumor continued to grow, indicating that a type of M phi is the effector cell essential for the rejection. In contrast to other well-known M phi s, the cytotoxic activity against Meth A cells was cell-to-cell contact dependent and soluble factor (e.g., NO and TNF-alpha) independent. Moreover, the cytotoxic activity of the M phi s (H-2b) against 51Cr-labeled Meth A (H-2d) cells was inhibited by the addition of unlabeled H-2d, but not H-2b, H-2k or H-2h, lymphoblasts as well as Meth A cells, implying the specific interaction of the M phi s with H-2d cells.

Molecular structure and function of CD4 on murine egg plasma membrane

In the present study, the expression of the CD4 molecule on murine egg plasma membrane was confirmed by the indirect immunofluorescence (IIF) method. The full-length CD4 cDNA from murine eggs was synthesised by the reverse transcriptase-polymerase chain reaction (RT-PCR) method and its authenticity verified by Southern blot hybridisation using an end-labelled internal oligonucleotide. The results of DNA sequencing showed that the nucleotide sequence of the cDNA of CD4 from murine egg mRNA was identical to that of immune T cells. To demonstrate the direct interaction of CD4 from murine egg with murine sperm cells bearing MHC (major histocompatibility complex) class II molecule, we employed a baculovirus expression system to generate CD4 on the surface of Spodoptera frugiperda (Sf9) cells. Expression of CD4 on Sf9 cells infected with Autographa californica nuclear polyhedrosis virus (AcNPV)-CD4 was demonstrated by IIF and immunoblotting. The CD4-expressing Sf9 cells adhered to MHC class II-bearing sperm cells since the adhesion was specifically blocked by anti-CD4 monoclonal antibody (mAb) or anti-monomorphic region of MHC class II mAb. Taking our previous and present experimental results together, they strongly suggest that intercellular membrane adhesion between two gametes at the fusion step in fertilisation is mediated by the MHC class II molecule located on the posterior region of the sperm head and the CD4 molecule on egg plasma membrane.

Specific prolongation of allograft survival by a T-cell-receptor-derived peptide

Allograft rejection results from the specific recognition by host CD8+ T cells of allogeneic major histocompatibility complex (MHC) molecules on the tissue graft. The specificity of this cellular response is determined by the molecular interaction of the T-cell receptor (TCR) on host T cells with the MHC molecule and its bound ligand on the grafted tissue. To better understand the precise manner by which the TCR interacts with the MHC-peptide complex and how to therapeutically intervene, we have studied the allogeneic response to the mouse class I MHC molecule Ld. In this report, the therapeutic potential of a synthetic peptide derived from the TCR V beta 8 variable region that predominates in responses to Ld was tested. This V beta 8-derived peptide was found to dramatically and specifically block the in vivo and in vitro allogeneic response to Ld. Furthermore, this specific blocking is not dependent upon the presence of V beta 8+ effector cells nor does the V beta 8 peptide bind to the Ld ligand binding cleft. We propose that this peptide functions as an antagonist, competing with the native TCR for recognition of the Ld molecule.

Donor major histocompatibility complex (MHC) peptides are presented by recipient MHC molecules during graft rejection

Peptides from donor major histocompatibility complex (MHC) molecules were examined for their activation of allogeneically primed T cells. After immunization with either allogeneic spleen cells or a skin allograft, primed T cells proliferate in response to peptides derived from polymorphic regions of alpha and beta chains of class II allo-MHC molecules. The results demonstrate that presentation of donor-MHC peptides by host-derived antigen-presenting cells is a common event in vivo. Thus, self-restricted T cell recognition of processed alloantigens may play a critical role in transplantation. An in-depth understanding of this response may result in the development of additional molecular therapies to combat allograft rejection.

Expression of CD4-like structure on murine egg vitelline membrane and its signal transductive roles through p56lck in fertilization

Expression of CD4-like molecule on vitelline membrane of murine eggs was demonstrated by indirect immunofluorescence (IIF) test and immunoprecipitation corresponding to the expression of major histocompatibility complex (MHC) class II molecule on murine sperm detected by immunoblotting. This molecule showed slightly larger size than that of the authentic CD4 molecule from T-cells on SDS-PAGE. This molecule was suggested to bind to MHC class II structure on sperm during fertilization because anti-CD4 monoclonal antibody (mAb) blocked in vitro fertilization (IVF). In addition, src-related tyrosine protein kinase (p56lck) was demonstrated in the inner vitelline membrane of eggs by means of IIF with anti-p56lck mAb and immune-complex kinase assay. This molecule was suggested to be associated with CD4-like molecule.

MHC antigens on human tumors

MHC class I antigens on tumor cells are expected to play an important role because they regulate the sensitivity to antitumoral immunological mechanisms. Overall or selective qualitative or quantitative changes in MHC molecules may modify the recognition of tumor cells by components of the immune system. It seems clear that MHC antigen expression on tumor cells is important in triggering the immune response by autologous lymphocytes. A deficiency in or lack of MHC class I antigens may have profound effects on T and NK cell activity. In experimental models, variation in the expression of MHC class I antigens has been shown to exert a decisive influence on local tumor growth and metastasis. However, there is little information about the influence of selective loss of individual locus products on the behavior of human tumor cells. Total and selective HLA losses have been found in a large variety of tumors, and different mechanisms have been shown to be responsible for these changes. In some examples, HLA losses are associated with a poor degree of tissue differentiation and poor prognosis. In other tumors, however, no such association has been found. We do not know whether HLA class II expression in neoplastic cells plays an immunological role, although, with the exception of melanoma, HLA class II expression is more frequently observed in tumors with a more favorable prognosis. Finally, there is no doubt that we need to learn more about how to manipulate the expression of MHC class I and II antigens in human tumors, in order to stimulate immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

Minor histocompatibility antigens

Histocompatibility antigens have been studied for over 50 years because they form a major obstacle to clinical transplantation. Human minor histocompatibility antigens remain ill-defined, but minor histocompatibility loci have been mapped on nearly every mouse chromosome. Recent molecular definition of several transplantation antigens suggests that they are by-products of an immune system poised to present viral antigens, and a mutation in any gene may give rise to a new minor histocompatibility antigen.

Binding of foreign DNA to mouse sperm mediated by its MHC class II structure

By means of radioimmunoassay, the expression of the major histocompatibility complex (MHC) class II molecules on murine sperm cells was clearly demonstrated as well as by our previous enzyme immunoassay (Mori T, et al. The expression of class II major histocompatibility antigen on mouse sperm and its role in fertilization. Am J Reprod Immunol. 1990; 24:9-14). The present study revealed that the site of sperm for binding foreign DNA was mediated by the complex structure of the MHC class II molecules localized at the posterior region of sperm head. This binding activity of sperm was time-, temperature-, and viability-dependent and completely inhibited by the treatment of sperm cells with mouse anti Iak serum, but not with mouse normal serum. Scatchard analysis of this binding activity also showed a single receptor type on sperm cells. These results were directly confirmed morphologically by taking autoradiography of sperm cells binding foreign DNA.

HLA-DR expression is associated with excellent prognosis in squamous cell carcinoma of the larynx

We studied class II antigen expression and tumor-infiltrating leukocytes (TIL) in tissue sections of 69 squamous cell carcinomas of the larynx and 24 lymph node metastases in the neck. HLA-DR expression was found only in eight well-differentiated, highly keratinizing squamous cell carcinomas comprising seven of the verrucous variety and one ventriculosaccular tumor. None of the metastases was positive for DR antigen. Neither primary tumors nor autologous metastases stained for DP or DQ antigens. DR-positive tumors shared a peculiar pattern of TIL composed mainly of T cells, most of which belonged to the cytotoxic/suppressor subset, and B cells. These neoplasms had in common a slow rate of growth, and are considered low-grade carcinomas in the literature. We conclude from our study that HLA-DR expression seems to characterize tumors with a prominent infiltrate and an excellent prognosis.

Molecular analysis of H-2 class I molecules expressed on the UV-induced tumour 1591

We have biochemically characterized by 2D (two-dimensional) electrophoresis three novel class I molecules called A166, A149 and A216 expressed by 1591, a UV-induced fibrosarcoma, and have compared them to class I molecules expressed by mice of the H-2q and H-2s haplotypes. A166 and A149 are very similar if not identical to Dq and Lq respectively. We have shown, using HPLC (high-pressure liquid chromatography) tryptic peptide mapping, that the expression of A166 is approximately three fold greater than A149, reminiscent of Dd compared to Ld. In addition A216 possess an identical isoelectric point to that of the Ks molecule. We demonstrate that outbred Swiss Webster mice express an analogous constellation of class I molecules and we conclude that our results can be most easily interpreted in terms of an allogeneic origin for the novel class I molecules expressed on 1591.

Transplantation resistance to a murine plasmacytoma lacking MHC determinants

A spontaneously arising murine plasmacytoma, HPC-202, derived from a BALB/c.H-2b congenic mouse that lacks any detectable H-2 determinants on its cell surface is described. However, the expression of H-2 determinants is inducible by interferon-gamma. The H-2 negative cell surface phenotype permits the HPC-202 tumor to escape H-2 allospecific cytotoxic cell lysis but not NK cell lysis, as well as to grow, to varying degrees, in some H-2 incompatible hosts. In those strains which exhibit a resistance to HPC-202 growth, resistance does not map to a single gene within the major histocompatibility complex of the mouse. Resistance is also radiosensitive and is therefore presumably due to a rapidly dividing cell population. The utility of this tumor as a model system to study both the non-H-2-restricted natural resistance to tumor growth, and the mechanism by which H-2 genes are regulated by cells is discussed.

Alien antigens return to the fold

Theories rationalizing major histocompatibility complex (MHC) class I polymorphism and the high frequency of alloreactive T lymphocytes initiated the search for expression of genetically inappropriate MHC class I molecules by tumour cells. Many examples of such 'Alien Antigens' have been reported in the past fifteen years. Some were previously shown to result from a variety of serological artefacts. Recent papers describe structural and genetic analysis of two extensively studied and outstanding systems. In both cases the Alien Antigens are also artefacts, resulting from genetic heterogeneity in either mice or cell lines. No Alien Antigens have survived rigorous evaluation and they are unlikely to constitute a significant biological phenomenon. It is also unlikely that the successive experimental plagues that created the Alien Antigens are unique to this corner of tumour immunology. Sophisticated innovation in experimental systems makes much immunological investigation increasingly dependent on the genetic integrity of mice and cell lines.

I-A alpha polymorphic residues that determine alloreactive T cell recognition

An individual's T lymphocytes are highly reactive to allogeneic MHC molecules. As a step in deciphering the mechanism of allorecognition by T lymphocytes, we have attempted to identify the TCR's target on MHC class II molecules, in particular the polymorphic residues that determine the specificity of recognition. We have generated a panel of Ak-reactive, Ab-nonreactive T cell hybridomas, and sets of L cell transfectants displaying A alpha A beta molecules with wild-type, chimeric or single site-mutated A alpha chains, with reciprocal interchanges between Ak and Ab. We then measured the stimulation of the T hybridomas in response to the transfectants. The results indicate that the hybridomas recognize diverse and complex determinants, with contributions from both A alpha and A beta chains, and from several regions or amino acids of the A alpha chain. The data are most consistent with a model in which alloreactivity results from the presentation of peptides to the T cell by an allogeneic MHC molecule, peptides that cannot be presented by the responder's own MHC complexes. The specificity of allorecognition seems to be imparted mainly by peptide/MHC molecule rather than TCR/MHC molecule contacts.

Creation of H-2 class I epitopes using synthetic peptides: recognition by alloreactive cytotoxic T lymphocytes

A major role that cytotoxic T lymphocytes (CTLs) play in the immune response is the specific destruction of viral-infected cells and tissue from foreign grafts. Class I molecules encoded within the major histocompatibility complex are the target structures for these CTLs. Recently, viral-restricted CTLs have been shown to recognize viral peptides in association with class I molecules, while several studies with cloned alloreactive CTLs have indicated that these T cells can recognize class I-derived peptides in association with class I molecules. Together, these observations suggest that peptide binding is an important function of class I molecules. In this paper, we show that the recognition of a particular class I molecule by a bulk population of alloreactive CTLs can be altered by incubating with it a peptide derived from another class I molecule. Specifically, we used the hybrid D/Ldm1 molecule as a target structure together with the peptide Ld61-85, and we have shown that their associative recognition by Ld-specific CTLs depends on sequence and configuration of the peptide and is specific for Ld using a cold-target inhibition assay. Our results are discussed in light of three possible models for the target structure(s) that can be recognized by alloreactive CTLs and in terms of the role peptides may play during allorecognition.